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Reinf. Conc. Wall Bearing on a Slab

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otto_eng

otto_eng

Civil/Environmental
Jun 27, 2017
88
Hi folks,

Has anyone of you designed a reinf. conc wall which is terminating on the slab that is above a parking space so the walls are not terminating at the foundation.
I would design the wall as a deep beam if I had any support points for the wall but unfortunately I do not have any beams or columns on either side of the wall so that is why I am exploring different options which makes sense both theoretically and practically.
I would be curious if I could consider it as a reverse T- shape beam slab being the flange and wall the web..
Do you guys have any refernce on the matter or any experience on a similar or same situation in the past ?
 
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You still don't have any support for the web, so how is the "reverse T-shape" helping you?
 
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here is my thinking process :
rc.wall.on.slab_vbahtf.png
 
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The deep beams with cantilever at the right should be okay. They do not rely on the slab for support.

The walls at the left are not straddling two beams, so they rely on the shear and bending capacity of the slab (which would need to be checked to see if it is adequate).

In neither case does the "reverse T-shape" have anything to do with the problem.
 
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Is this for works being done to an existing structure? otherwise i assume you would simply move the beams or make it a flat plate transfer slab?
 
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The building is not in a seismic zone and it is not an existing structure.
 
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In this case what is hindering ? just shift the beam axis and provide at least two supports.



He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 
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Unfortunately moving the beams is not an option otherwise I’d have done that ..
 
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loti_eng said:
I would be curious if I could consider it as a reverse T- shape beam slab being the flange and wall the web..
Click to expand...

I could probably get behind that, using the slab to bridge the door openings for deep beam flange forces etc.

You'll want to either shore the slab below the walls or consider how the wet weight of concrete in the walls will tax the slab.

You will, of course, need enough wall meat above the doors to resolve beam shear there.

Be realistic about where the walls will likely deliver point loads to hard spots in the supporting slab.

c01_d5wvxz.jpg
 
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It's very hard to give you an opinion with very limited information. Where i live, a slab like this would typically be built as a two-way flat plate transfer slab to keep the overall slab depth and formwork costs to a minimum. Personally, i am hesitant to use walls to span like you have described. In my experience, implementing these sorts of systems end up being more trouble than they are worth.
 
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Not a problem... other than discontinuities at ends of wall and corners. Just normal dowels from the slab to the wall, unless shear. Due to deflection, these dowels may be in tension. About 40 years back, I designed a 20 storey shear wall transfer beam considering the load from the shear wall as point loads at the ends of the wall, and not as a UDL. Reinforcing was greatly reduced for both shear and flexure. Connection from the precast wall panel over was for tension.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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dik, i think its a practicality issue more than anything. For example, you mentioned precast walls, but if you use precast walls over then the whole slab needs to be continuously propped until the precast dowels are grouted and cured. Otherwise the slab is partially loaded before the slab and walls can act together. Most likely the builder won't really understand this or budget for it, so it can very quickly become a real headache, that's been my experience anyway.
 
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These were coming down on a transfer beam, not a slab. The illustration was that the dowels can be loaded in tension, depending of deflection issues.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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